How much light do different crops need?

There is an optimal amount of light for every crop. At lower levels, plant production levels fall. But too much light also depresses yield and quality. So customization is vital. Here, ReduSystems shares a list of light levels tailored to specific crops.

Tomatoes and cucumbers
(MAX. 30 MOL/M2) 
These crops love light. They can usefully convert as much as 30 mol of light per m2 per day* into production. That means conversion is not particularly fast. So, in winter low-light regions, improving light penetration helps. You can do so by using AntiReflect to reduce light reflection on the greenhouse. On the inside, AntiCondens creates a fine film of water on the structure's ceiling instead of large droplets of condensation. That, too, significantly improves light penetration.

Crops in greenhouses without coating get a lot of sun hitting their tops and too little further down the plants. You can use a diffuse coating to improve that. The plants' lower leaves then also become more productive, thus, improving yield and quality. The diffuse light, with no alternate shade and sun spots, ensures calm, stress-free growth.

When using a high light level, you must ensure that the plants never get too hot. You can achieve this with ReduHeat, which selectively blocks heat radiation. The crop can fully assimilate while temperatures are kept low. You can get the same results using ReduFuse IR, which combines the advantages of diffused light with heat inhibition. In hot, dry areas, light inhibition is unavoidable in the summer. Then using ReduSol and possibly an additional SprayChalk layer are appropriate remedies.

Bell peppers
(MAX. 25 MOL/M2)
Bell peppers like the light, but not as much as tomatoes or cucumbers. Basically, the same as above applies to this crop. Only, in the hot months, you will have to begin using a screening agent sooner. That is all the more important because, in sweet bell peppers, fruit setting and its growth are always in competition. Heat stress quickly unbalances these two processes. Extra attention to heat stress pays off, and both ReduFuse IR and ReduHeat can benefit bell peppers' growth.

(MAX. 15 MOL/M2)
Lettuce has very different demands. Its optimal light level is half that of tomatoes. So, you have to use coating differently, too, and what is sensible is highly dependent on the region. If the light level inhibits production over a long period, you would do well to consider coatings that improve light penetration. But, especially in warmer regions, inhibiting light is the key. And, for part of the year, certainly heat levels, with coatings like ReduSol and possibly SprayChalk.

Roses and chrysanthemums
(MAX. 22-30 MOL/M2)
Roses and chrysanthemums, like tomatoes and cucumbers, love light. That means coating use is similar. However, there is one important caveat. Flowers and buds are often sensitive to heat stress; some colors far more than others. So, you need to pay extra attention to heat protection. In roses, the ReduFlex Blue coating is becoming popular. It combines heat protection with selective blue light inhibition. That lengthens rose stems and positively affects flower quality.

Other cut flowers
Many cut flowers are in the mid-category. They like quite a lot of light, but not too much. That means you should start using particularly sunscreen coatings earlier in the year than for roses and chrysanthemums. These crops also definitely benefit from diffused light.

Potted plants
(MAX. 4-12 MOL/M2)
Most potted plants are true shade plants. For much of the year, you must protect them from both high light levels and too much heat. Then, ReduSol is the appropriate coating. Some species - for example, fuchsia and hydrangea - can handle a slightly higher light level. Depending on the region and location, the ReduFuse IR heat-resistant diffuse coating might be an idea.

Wageningen University & Research studies show that several potted plant varieties can handle more light than is typically used in practice. In tests, higher light levels resulted in faster production times and much heavier plants. An absolute condition: there must be no heat stress, and humidity must not drop too low. Diffuse light and humidifiers achieve that. Dutch growers apply diffuse coating more often, thus realizing higher, faster production.

Choosing the right coating depends not solely on the crop but also on climate conditions and the type of greenhouse. Wondering which coating will help you get the most out of your crop? The ReduWizard provides personal advice online, and account managers are always available to answer questions.

*Maximum mol per m2 is an indication. These numbers are based on Purdue University data.

Source: ReduSystems

For more information:
Lumiforte Holding BV
8 Geer Street
5111 PS, Baarle-Nassau, NL
Tel.: +31 (0) 135 075 399

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